Materials that can be used to provide electro-optical signature reduction, termed low observable coatings, are desirable for use in military vehicles to provide resistance to visibility in both the visual and/or infrared spectrums. Prior camouflage Chemical Agent Resistant Coatings (CARC) were developed to address low visibility needs in the visual and near infrared (IR) bands. For example, the three color woodland pattern and the desert tan match the visual effects of the background, and in the near IR the green color matches the sharp reflectance rise of chlorophyll present in all green foliage. In 1985, CARC became the standard camouflage coating for the Army as: MIL-C-46168, based on a two component urethane consisting of a aliphatic diisocyanate and a saturated polyester.
Unfortunately, the original CARC materials were deemed unsuitable for continued use due to poor performance and high volatile organic content (VOC) resulting from the use of the materials used in the formulation of CARC. In response, a water dispersible CARC was formulated as described in U.S. Pat. No. 5,691,410. While this material addressed the environmental concerns, it has become increasingly clear that the long dry times required for cure of these CARC materials is a detriment to their wide scale use.
As such, new compositions suitable for use in low observable coatings are needed.